Treatment of human cancer is an area of clinical medicine which remains fraught with complications and which often presents an array of suboptimal treatment choices. For example, prostate cancer, which is the most common cancer in men and the second leading cause of cancer death in men, can be treated surgically or medically or with a combination of both depending on the state of advance of the cancer. Other than hormonal therapy, no agents are available to treat prostate cancer that are without substantial toxicity. Frequently, cancer occurs in debilitated patients who are either not surgical candidates or who could not tolerate conventionally available chemotherapeutic agents.
Radiation therapy (X-ray treatment) is one modality available to treat selected cancers. It is used at many stages in the treatment of prostate cancer. For example, it can be used as an alternative to surgery to treat localized prostate cancer. X-ray therapy can also be used in metastatic prostate cancer to treat local deposits of tumor that threaten key organs such as the spinal cord. Radiation can be useful to treat a number of cancers in settings such as to attempt the cure of local tumor and the symptomatic management of troublesome metastatic disease.
Osteosarcoma is an example of a cancer primary to the bone but which can metastasize and which remains a major tumor problem in children. A subtype of osteosarcoma, chondrosarcoma, does not metastasize. However, chondrosarcoma often recurs locally after surgical excision and it can require more than surgery alone. Glioblastomas are malignant tumors which do not metastasize generally but which are commonly beyond surgical cure, with median patient survivals of less than one year. A rapidly growing primary tumor that is not surgically curable can cause significant morbidity and mortality without necessarily metastasizing. In such a case, effective chemotherapy is needed.
More generally, a chemotherapeutic agent which possesses little or no toxicity, which is inexpensive to obtain or manufacture, which is well tolerated by the patient, and which is easily administered would be a desirable addition to the array of therapeutic modalities available to the oncologist. Such a chemotherapeutic agent could find application in treatment of cancers which are metastatic, locally expanding or locally invasive. Additionally, such an agent could be useful if it were to sensitize the cancer to radiation therapy. Thus, the cancer would respond more readily to X-ray treatment.